How to support powershell tab expansion in psprovider?

I'm implementing Powershell PSProvider for some internal hierarchical data. Everything works fine, I can navigate through the tree with usual cd/dir commands, the only thing doesn't work is tab completion.

What I can see is that Powershell calls function GetChildName() with an asterisk in the path when Tab is pressed (if I type "dir c" and press Tab, GetChildName() function will be called with string "c*", several times). I tried to return all child names from the folder that begins with "c", but Powershell always displays ju开发者_如何学编程st the first child name in the front. I can't find any documentation about this behavior, what I'm missing?

Are you sure you aren't just seeing normal behavior? With the default Tab Expansion, you will only see the first result. Pressing tab additional times will cycle through the list of returned results from the provider.

There are some quirks with providers. I have been working on one using the Script Provider project. I put debug code in all my methods to see which ones PowerShell was calling, when, and with what arguments.

I found where's the problem - function GetChildName() in the provider shouldn't try to expand given file name if asterisk is part of the name; The function should return child name if it can find an exact match, or call base.GetChildName() in any other case. Something like this:

protected override string GetChildName(string path) {
    string name = SomeFunctionThatTriesToFindExactMatchForGivenPath(path);

    if(string.IsNullOrEmpty( ret ) )
        ret = base.GetChildName( path );

    return ret;
}

BTW, I found that default tab expansion is very forgiving about stuff that can be returned from GetChildName() function - even if return value have slash/backslash in the front/back, tab expansion will work. But PowerTab, popular tab expansion module, is much more picky about return values.